SPET-generated colour-coded polar maps to quantify 99Tcm-MIBI and 123I-BMIPP uptake in chronically dysfunctional myocardium: comparison with coronary anatomy and wall motion.
The combined use of 123I-BMIPP and 99Tcm-MIBI SPET imaging has been proposed as an alternative to PET for the non-invasive detection of jeopardized myocardium after a myocardial infarction, a mismatch accurately indicating jeopardized but still viable tissue. In this paper, a new quantitative approach is described, expressing the presence and degree of mismatch as the percentage of the left ventricular surface globally as well as for each major epicardial artery by means of clearly identified colour-coded polar maps. With this method, the relative proportion of normal and scar tissue, each characterized by a specific colour, is measured using thresholds of 99Tcm-MIBI uptake of 60% and 30% of the expected mean normal value respectively, whereas the presence and extent of mismatch between 99Tcm-BMIPP and 99Tcm-MIBI are calculated only between these two thresholds, typically corresponding to a reduction in flow associated with a possible but uncertain post-revascularization recovery. Applied to 15 patients with severely impaired left ventricular function after a myocardial infarction, small intra- and inter-observer differences were noted in the assessment of the relative proportion of normal, mismatched and scar tissue. More specifically, analysing the variability in the calculated percent mismatch, good reproducibility was observed, with intra- and inter-observer correlation coefficients of 0.96 and 0.94 respectively, a mean (+/- S.D.) intra-observer difference of 0.25 +/- 2.0% for the left ventricle globally, 1.65 +/- 2.9% for the left anterior descending artery (LAD), -1.56 +/- 3.6% for the left circumflex artery (LCX) and -1.24 +/- 2.8% for the right coronary artery (RCA) territories, and mean inter-observer variability of 0.91 +/- 2.4% for the left ventricle globally, -1.51 +/- 3.0% for the LAD, -0.53 +/- 2.9% for the LCX and -0.34 +/- 3.9% for the RCA territories. Using the second standard deviation of the inter-observer difference as a criterion of significance, a significant mismatch between 99Tcm-BMIPP and 99Tcm-MIBI was noted in 13 arterial territories, corresponding to significant stenoses on coronary angiogram and/or wall motion abnormalities in all cases. These results suggest that this new quantitative method, showing good reproducibility, may constitute a reliable and interesting tool for the non-invasive evaluation of myocardial viability with SPET.
Hambÿe
A S
AS
Middelheim General Hospital, Antwerp, Belgium.
Dobbeleir
A
A
Franken
P R
PR
D000368:Aged; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D005227:Fatty Acids / Q000493:pharmacokinetics; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D007462:Iodobenzenes / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism; D015588:Observer Variation; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D017256:Technetium Tc 99m Sestamibi / Q000493:pharmacokinetics; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000503:physiopathology
D005227:Fatty Acids; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D019275:Radiopharmaceuticals; C049338:iodofiltic acid; D017256:Technetium Tc 99m Sestamibi